patch "iio: health: max30102: fix NULL dereference in interrupt handler" added to char-misc-linus

This is a note to let you know that I've just added the patch titled

iio: health: max30102: fix NULL dereference in interrupt handler

to my char-misc git tree which can be found at
git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc.git
in the char-misc-linus branch.

The patch will show up in the next release of the linux-next tree (usually sometime within the next 24 hours during the week.)

The patch will hopefully also be merged in Linus's tree for the next -rc kernel release.

If you have any questions about this process, please let me know.

From f0ea4824deebf21dacfbe397c4b0a5fd3e745a8d Mon Sep 17 00:00:00 2001
From: Marco Chen <[email protected]>
Date: Sat, 8 Aug 2026 15:54:50 -0400
Subject: iio: health: max30102: fix NULL dereference in interrupt handler

The interrupt is requested in max30102_probe() and stays enabled for the lifetime of the device, but indio_dev->active_scan_mask is only valid while a buffer is enabled. When an interrupt arrives while no buffer is enabled, the handler dereferences the NULL active_scan_mask:

  Unable to handle kernel NULL pointer dereference at virtual address 0000000000000000
  Call trace:
   __bitmap_weight+0x64/0x98 (P)
   max30102_interrupt_handler+0x48/0x160 [max30102]

Call max30102_fifo_count() at the top of the handler and return early unless it reports a FIFO sample is ready. Because FIFO_RDY is the only interrupt source enabled in max30102_chip_init(), an invocation of max30102_interrupt_handler() without the FIFO_RDY interrupt status bit set carries no data to read and can return before touching active_scan_mask. A negative return from max30102_fifo_count() indicates a failed interrupt status read and is treated the same way.

---
 drivers/iio/health/max30102.c | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

index c37316c86f14..aee96167f01e 100644
@@ -290,9 +290,15 @@ static irqreturn_t max30102_interrupt_handler(int irq, void *private)
 {
 	struct iio_dev *indio_dev = private;
 	struct max30102_data *data = iio_priv(indio_dev);
-	unsigned int measurements = bitmap_weight(indio_dev->active_scan_mask,
-						  iio_get_masklength(indio_dev));
-	int ret, cnt = 0;
+	unsigned int measurements;
+	int ret, cnt;
+
+	cnt = max30102_fifo_count(data);
+	if (cnt <= 0)
+		return IRQ_HANDLED;
+
+	measurements = bitmap_weight(indio_dev->active_scan_mask,
+				     iio_get_masklength(indio_dev));
 
 	mutex_lock(&data->lock);
 

2.55.0